1. Field of the Invention
The present invention relates in general to the field of lighting. More particularly, the present invention relates to remote lighting systems that have a remotely located light source. The systems can be adapted and configured to address the particular requirements of an intended use. The present invention thus relates to a lighting system of the type that can be termed universal remote.
2. Discussion of the Related Art
Within this application several publications are referenced by arabic numerals within parentheses. Full citations for these, and other, publications may be found at the end of the specification immediately preceding the claims. The disclosures of all these publications in their entireties are hereby expressly incorporated by reference into the present application for the purposes of indicating the background of the present invention and illustrating the state of the art.
Historically, it was known in the prior art to provide airports with high energy approach lighting systems. Although the configuration of airport lighting systems has been optimized through years of experience, the current approach lighting systems approved by the United States Federal Aviation Administration (FAA) are probably among the oldest aviation technologies.
The conventional aircraft approach lighting system.sup.(1) includes groups of incandescent lamps distributed over a field, lighting several thousand feet of the approach to the runway with specific requirements for angular light distribution and intensity. The present system used to monitor and control the light given off by this approach lighting system (ALS) is based on an indirect monitoring method that is subject to false indications caused by variations in loop current and lamp impedance, aging effects and other factors.
A major problem with the currently used approach lighting system is light source failure. The number and location of failed lamps are critical parameters for permission to use a full approach lighting system. Lamp exchange is a significant maintenance expense.
Another problem with the currently used approach light system is that the steel towers which are presently used to support most runway approach lights create a significant collision hazard to any aircraft which approaches the runway below the proper glide path envelope. Since the separation between the proper approach path and the approach light plane decreased as the landing aircraft nears the runway threshold, the innermost towers present the greatest hazard to landing aircraft. Any new runway construction requires the installation of fragile or semi-fragile lights between the runway threshold and the 1000-foot bar. Current FAA plans call for the replacement of the existing steel towers by fragile towers.
According to ICAO and FAA regulations, currently used ALSF-2 systems must operate at 5 brightness levels, depending on the time of day (day or night), weather, visibility, and other related conditions. As a function of the selected brightness, the regulated constant current can be set at 5 discrete values. Control and monitoring of the current are provided by an electronic subsystem. This subsystem measures and regulates only electrical parameters, maintaining a constant output current. For several reasons, such as, for example, the dispersion parameters of individual incandescent lamps, aging, difference resistances in current loops, etc., even with perfect monitoring of the output current, the brightness of the lamps varies across the field. Thus, the imperfect control and monitoring that is an inherent feature of the presently used approach lighting system is another problem.
What is needed therefore is an approach lighting system having higher reliability, safer structures and a monitoring system that is less prone to false indications. What is also needed is an approach lighting system with higher efficiency, including lower maintenance costs.
In an attempt to solve these problems, various engineering solutions have been implemented. All of the control and monitoring systems proposed to date have been based on indirect measurement of the brightness of the light at the lighting point (i.e., the intensity of the visible light concentrated on a desired spot.) For example, one solution used a system in which a small radio transmitter sent information about the status of each lamp to the air traffic control tower.
These previously recognized solutions have the disadvantage of relatively high cost. Providing aircraft approach lighting systems for the world-wide market is a competitive business. A preferred solution will be seen by the end-user as being cost effective. A solution is cost effective when it is seen by the end-user as compelling when compared with other potential uses that the end-user could make of limited resources.
It was also known in the prior art to provide ships with navigation lighting systems with specific requirements for intensity, angular light distribution and light color. Similarly, aircraft and automobiles have been provided with navigation lighting systems. Lower weight, lower cost, higher reliability and higher efficiency, including lower maintenance costs, is also needed for these navigation lighting systems.
The below-referenced U.S. patents disclose embodiments that were at least in-part satisfactory for the purposes for which they were intended. The disclosures of all the below-referenced prior United States patents in their entireties are hereby expressly incorporated by reference into the present application for purposes including, but not limited to, indicating the background of the present invention and illustrating the state of the art.
U.S. Pat. No. 4,309,093 discloses a method of replicating a diffusing plate. U.S. Pat. No. 4,336,978 discloses a method for optically making a diffusion plate. U.S. Pat. No. 4,898,450, discloses an expanded beam nonimaging fiber optic connector. U.S. Pat. No. 5,365,354, discloses method of making a GRIN type diffuser based on volume holographic material.